no longer allows backtracking, no longer allows line crossing

there is a bug somewhere between the line crossing and backtracking
where if it stops backtracking it will still allow line crossing
Kyle and my code merged
Merge branch 'gui-merging' of https://github.com/floft/sprouts into gui-merging
Test

Work on preventing line crossing on final click
Node Connection to not cross

Horizontally connecting to node is having problems.
Merge branch 'gui-merging'

Conflicts:
	gamegui.cpp